class_docstr: A mock act gen.
    
code: def get_examples_for_concept(self, concept):
      return []
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from tcav.activation_generator import ActivationGeneratorBase
  from tcav.cav import CAV
  from tcav.tcav import TCAV
  from tensorflow.python.platform import googletest
  import numpy
  import tensorflow
label_desc: Use image node_id 2 for calling the TcavTest_ActGen obj's underlying member method code with example usage: obj.get_examples_for_concept(concept) and returns: list